In the operation of various types of storage facilities such as, for example, the warehouse of a metal fabricating plant or the loading platform of a wharf, it often happens that cranes are required to hoist and transport articles of greatly varying shapes and sizes. For example, in the operation of a metal fabricating plant, a crane may be required in one instance to hoist and transport a box or a load of relatively compact articles having typical dimensions of, for example, 4.times.4.times.6 feet, and in another instance be required to hoist and transport an elongated article such as a steel plate or a girder having a length of perhaps 50 feet or more. Present day storage facilities generally employ one of several different approaches to the design of cranes required to perform such multiple functions. One of these approaches is to use a crane with two or three trolleys mounted for travel along its bridge. Such cranes may consist of, for example, four-girder bridge cranes with a larger trolley mounted on the two outside girders and a smaller trolley, which operates underneath the larger trolley, mounted on the two inside girders. Alternatively, two, three or more trolleys are mounted for operation on the same set of girders. In either case, the trolleys are operated in tandem when elongated loads are hoisted and transported, one trolley, for example, hoisting one side of the article and another trolley hoisting the other side. An alternative approach is to simply employ two or three cranes such that when elongated loads must be hoisted and transported, the cranes are operated in tandem. Each of these approaches has disadvantages which include relatively high costs of installation and complex operating procedures.